My plan is to give each forum/sub its own subdomain. So while Reddit would have https://www.reddit.com/r/snakes/ , FreedIt would have https://snakes.freedit.org/ . This way each forum is a separate site on luan hosting and can be completely controlled by the site owner. But I remember you said that there is a problem with many HTTPS certificates for one domain. Someone suggested this:
"If you combine both subdomains in a single certificate by using the -d option twice in the same certbot command, you’ll get a single certificate which will count as just one. You can enter up to 100 (sub)domain names in a single certificate."